Study of the complex between the contrast agent Iobitridol (Xenetix) and Elastase (PPE): a model for hydrophobic site protection in drug-protein interactions.
OBJECTIVE
The concept of Hydrophilic Sphere Stabilization, or Hydrophobic Shielding, has been postulated in the synthesis of biocompatible contrast agents in vascular imaging. To improve the safety of these polyiodinated agents, interactions with protein hydrophobic sites in biomacromolecules should be kept as low as possible. In order to evaluate the level of interactions with proteins, we have selected the serine proteinase Elastase, in presence of Iobitridol (Xenetix), as a model.


METHODS
The complex between Iobitridol and Pancreatic Porcine Elastase was investigated by X-ray diffraction techniques, on saturated monocrystals, using the synchrotron radiation at 0.98A.


RESULTS
In contrast to Iohexol, which displays several interactions including one in the active site, Iobitridol is unable to interact directly with elastase. Only one partially occupied site is found in between two molecules of the crystal packing.


CONCLUSIONS
The validation of the "hydrophobic shielding" concept, which was at the origin of the design of the Iobitridol molecule, has been proven to be an essential feature in minimizing in vivo protein interactions.
Prangé
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Chimie Structurale Biomoleculaire (URA-1430 CNRS, Bobigny, France. prange@lure.u-psud.fr
Neuman
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A
Corot
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C
Meyer
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D
D000818:Animals; D001665:Binding Sites; D003287:Contrast Media / Q000737:chemistry*; D005583:Fourier Analysis; D007472:Iohexol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D010196:Pancreatic Elastase / Q000737:chemistry* / Q000378:metabolism; D013552:Swine; D014961:X-Ray Diffraction
D003287:Contrast Media; C093233:iobitridol; D007472:Iohexol; D010196:Pancreatic Elastase